Binary Black Hole with Athenak: Merging Black Holes on GPUs

We present recent progress on the open-source numerical relativity solver in Athenak, a successor to GR-Athena++. Athenak uses the kokkos performance portability libarary to fully take advantage of heterogeneous computing on exascale clusters. We show scaling results and compare the performance with cpu codes. We further discuss the adaptive mesh-refinement strategies and their impact on the accuracy of the waveform. We will also show early science results enabled by exascale computing.